The present invention relates in general to dental matrices for engaging around a tooth, and in particular to a new and useful dental matrix made primarily of plastic material and requiring no external retainer for retaining the matrix on a tooth.
Retainerless dental matrices are known from the Inventor's previous U.S. Pat. Nos. 3,411,214 granted Nov. 19, 1968 and 3,921,299 granted Nov. 25, 1975. These all-metal matrices utilize a cylindrical coil which can be engaged by a specially designed Dentist's coil winding tool for winding the coil against a lock loop to tighten and lock a band portion of the matrix around a tooth to be restored. These locked on matrices permit removal of the winding tool from the matrix, and the mouth. Thus this matrix is retainerless.
The winding tool is disclosed by the Inventor's U.S. Pat. Nos. 3,435,905 granted Apr. 1, 1969 and 3,852,884 granted Dec. 10, 1974.
Other types of dental matrices which require external retainers are also known from U.S. Pat. Nos. 606,420 to Ivory and 2,538,486 to Tofflemire. Said retainers project from Patient's mouth, blocking vision and cluttering the operative field.
Dental matrices of the type which must be tightened around a tooth have been made of metal due to the fact that a metal matrix band can be made sufficiently thin to fit in a space between the teeth while at the same time having sufficient strength to accommodate the forces necessary to firmly engage and lock on a tooth. The metal for dental matrices is usually maleable and work-hardenable stainless steel. The matrix is placed completely around the prepared tooth to be reconstructed or restored and then held tightly to the tooth by any of several retaining mechanisms. Filling material is then placed at appropriate locations in or on the tooth and allowed to harden. After this the band is removed. The filling material has conventionally been amalgam alloy or composite restorative materials consisting of hardenable resin which contains organic or inorganic fillers.
Various dental restorative materials are now known and widely utilized which are curable by visible or ultraviolet light. While utilizing such light-curable restorative materials in combination with the known metal matrices, which are opaque, presents an undesirable barrier to the beam of curing light when it is time to cure the restorative material. While a thin layer of restorative material is visible from the open occlusal area of the matrix can be cured by the light, composite material at and below the gingiva, proximal and floor of the tooth cannot be readily exposed to the light.
Some examples of light handenable restorative material are the restorative products sold under the tradename of NUVA-FIL which can be cured by ultraviolet light. More recently restorative material has been developed which can be cured by visible light such as those sold under tradenames of PRISMA-FIL and FUL-FIL. NUVA-FIL, PRISMA-FIL and FUL-FIL are tradenames for these restorative products which are produced by the L. D. Caulk Co. of Milford, Del.